CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current Assets
Cash and cash equivalents	$ 702.3	$ 11.9
Accounts receivable, net	555.7	408.5
Fair value of derivative contracts	0	0.2
Gas, oil and NGL inventories at lower of average cost or market	8.6	13.4
Deferred income taxes	50.7	30.6
Prepaid expenses and other	66.7	54.4
Total Current Assets	1,384.0	519.0
Property, Plant and Equipment (successful efforts method for gas and oil properties)
Proved properties	11,231.2	11,571.4
Unproved properties	1,120.1	665.1
Midstream field services	1,735.2	1,698.1
Marketing and other	92.1	85.5
Material and supplies	66.0	59.0
Total Property, Plant and Equipment	14,244.6	14,079.1
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	4,680.5	4,930.9
Midstream field services	441.1	409.7
Marketing and other	26.7	22.1
Total Accumulated Depreciation, Depletion and Amortization	5,148.3	5,362.7
Net Property, Plant and Equipment	9,096.3	8,716.4
Investment in unconsolidated affiliates	36.7	39.0
Fair value of derivative contracts	1.7	1.0
Restricted cash	0	50.0
Other noncurrent assets	44.1	51.4
TOTAL ASSETS	10,562.8	9,376.8
Current Liabilities
Checks outstanding in excess of cash balances	5.7	90.9
Accounts payable and accrued expenses	692.6	434.9
Production and property taxes	65.7	51.8
Interest payable	37.1	37.2
Fair value of derivative contracts	109.3	26.7
Total Current Liabilities	910.4	641.5
Long-term debt	3,910.8	2,997.5
Deferred income taxes	1,597.6	1,560.6
Asset retirement obligations	188.5	191.8
Fair value of derivative contracts	16.1	0
Other long-term liabilities	113.5	108.6
Commitments and contingencies
EQUITY
Common stock - par value $0.01 per share; 500.0 million shares authorized; 180.8 million and 179.7 million shares issued, respectively	1.8	1.8
Treasury stock - 0.7 million and 0.4 million shares, respectively	(23.0)	(14.9)
Additional paid-in capital	518.0	498.4
Retained earnings	2,857.9	2,917.8
Accumulated other comprehensive loss	(24.6)	(26.5)
Total Common Shareholders' Equity	3,330.1	3,376.6
Noncontrolling interest	495.8	500.2
Total Equity	3,825.9	3,876.8
TOTAL LIABILITIES AND EQUITY	$ 10,562.8	$ 9,376.8